changeset 7828:cd09f5af6ef1

8055949: ByteArrayOutputStream capacity should be maximal array size permitted by VM Summary: Try to resize to "well-known" hotspot max array size first. Reviewed-by: alanb, mduigou
author igerasim
date Wed, 17 Sep 2014 23:52:27 +0400
parents 3ffaec4e32f2
children 208ca35139b7
files src/share/classes/java/io/ByteArrayOutputStream.java test/java/io/ByteArrayOutputStream/MaxCapacity.java
diffstat 2 files changed, 83 insertions(+), 5 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/classes/java/io/ByteArrayOutputStream.java	Mon Nov 03 12:26:42 2014 -0800
+++ b/src/share/classes/java/io/ByteArrayOutputStream.java	Wed Sep 17 23:52:27 2014 +0400
@@ -94,6 +94,14 @@
     }
 
     /**
+     * The maximum size of array to allocate.
+     * Some VMs reserve some header words in an array.
+     * Attempts to allocate larger arrays may result in
+     * OutOfMemoryError: Requested array size exceeds VM limit
+     */
+    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
+
+    /**
      * Increases the capacity to ensure that it can hold at least the
      * number of elements specified by the minimum capacity argument.
      *
@@ -105,14 +113,19 @@
         int newCapacity = oldCapacity << 1;
         if (newCapacity - minCapacity < 0)
             newCapacity = minCapacity;
-        if (newCapacity < 0) {
-            if (minCapacity < 0) // overflow
-                throw new OutOfMemoryError();
-            newCapacity = Integer.MAX_VALUE;
-        }
+        if (newCapacity - MAX_ARRAY_SIZE > 0)
+            newCapacity = hugeCapacity(minCapacity);
         buf = Arrays.copyOf(buf, newCapacity);
     }
 
+    private static int hugeCapacity(int minCapacity) {
+        if (minCapacity < 0) // overflow
+            throw new OutOfMemoryError();
+        return (minCapacity > MAX_ARRAY_SIZE) ?
+            Integer.MAX_VALUE :
+            MAX_ARRAY_SIZE;
+    }
+
     /**
      * Writes the specified byte to this byte array output stream.
      *
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/io/ByteArrayOutputStream/MaxCapacity.java	Wed Sep 17 23:52:27 2014 +0400
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2014 Google Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @ignore This test has huge memory requirements
+ * @run main/timeout=1800/othervm -Xmx8g MaxCapacity
+ * @bug 8055949
+ * @summary Check that we can write (almost) Integer.MAX_VALUE bytes
+ *          to a ByteArrayOutputStream.
+ * @author Martin Buchholz
+ */
+import java.io.ByteArrayOutputStream;
+
+public class MaxCapacity {
+    public static void main(String[] args) {
+        long maxHeap = Runtime.getRuntime().maxMemory();
+        if (maxHeap < 3L * Integer.MAX_VALUE) {
+            System.out.printf("Skipping test; max memory %sM too small%n",
+                              maxHeap/(1024*1024));
+            return;
+        }
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        for (long n = 0; ; n++) {
+            try {
+                baos.write((byte)'x');
+            } catch (Throwable t) {
+                // check data integrity while we're here
+                byte[] bytes = baos.toByteArray();
+                if (bytes.length != n)
+                    throw new AssertionError("wrong length");
+                if (bytes[0] != 'x' ||
+                    bytes[bytes.length - 1] != 'x')
+                    throw new AssertionError("wrong contents");
+
+                long gap = Integer.MAX_VALUE - n;
+                System.out.printf("gap=%dM %d%n", gap/(1024*1024), gap);
+                if (gap > 1024)
+                    throw t;
+                // t.printStackTrace();
+                break;
+            }
+        }
+    }
+}